The present invention relates to pesticide compositions and methods for producing pesticide compositions. The disclosed compositions may include granular pesticide compositions and powder pesticide compositions which are prepared directly from liquid emulsions of the pesticide in solutions of lignosulfonate and which in turn may be reconstituted in water into stable emulsions.
Many pesticides are hydrophobic organic compounds. Some hydrophobic pesticide compounds have a relative low melting point, such that they exist as a liquid at room temperature. Other hydrophobic pesticide compounds having a higher melting point may be dissolved in an organic solvent to obtain a pesticide solution. In order to disperse the pesticide liquid or solution in water for easy application, the pesticide may be formulated as a water-dispersible emulsifiable concentrate. This process typically requires an emulsifying agent, which will cause an emulsion to form spontaneously when the concentrate is added to water.
Processed lignin is obtained as a by-product of wood pulping reactions and has been shown to be useful for a variety of commercial applications. For example, alkali soluble lignin has been used as a dispersing agent. U.S. Pat. No. 3,726,850 discloses the use of an alkali soluble, ozone-treated lignin product, which is essentially free of organically bound sulfur, as a dispersing agent for clays, dyestuffs, pesticides, carbon black and other materials. The '850 patent contrasts the use of alkali soluble, ozone-treated lignin material as dispersing agents with lignosulfonate dispersing agents. Furthermore, the '850 patent does not indicate whether the disclosed formulations are suitable for preparing granular pesticide formulations that may be reconstituted as emulsions.
U.S. Pat. No. 4,666,522 discloses the use of lignosulfonate products for preparing emulsions of waxes, oils, fats, asphalts, and mixtures thereof. However, the '522 patent does not disclose the use of high purity, high molecular weight lignosulfonates as emulsifying agents for hydrophobic, low melting point pesticides. Furthermore, the '522 patent indicates that a stable emulsion cannot be prepared unless the lignosulfonate concentration is 45-65%. The '522 patent also does not indicate whether the disclosed formulations are suitable for preparing granular pesticide formulations that may be reconstituted as emulsions.
U.S. Pat. No. 5,668,183 discloses the use lignosulfonate products for dispersing fat-soluble substances. However, the '183 patent does not disclose the use of high purity, high molecular weight lignosulfonates as emulsion stabilizers for hydrophobic, low melting point pesticides. The '183 patent indicates that suitable lignosulfonate products consist of 40-90% lignosulfonic acid, or its salts, and include various amounts of hygroscopic agents such as saccharides, ash, carbohydrates, acetates, formates, resins, etc. Lignosulfonate products that have relatively high sugar content also are taught as being suitable for the methods of the '183 patent. The '183 patent does not indicate that high purity lignosulfonates having low sugar content are desirable or even suitable for the disclosed methods. Furthermore, the '183 patent does not indicate whether the disclosed formulations are suitable for preparing granular pesticide formulations that may be reconstituted as emulsions.
Safer and more environmentally friendly emulsion stabilizers and carriers for pesticides are needed. Disclosed herein are high purity, high molecular weight lignosulfonate materials for preparing stable, dispersible pesticide emulsions. The prepared emulsions may be dried or granulated to obtain powder or granular pesticide formulations, which in turn, may be reconstituted with water to obtain stable, dispersible emulsions. The disclosed pesticide formulations exhibit many desirable characteristics such as stability, flowability, dissolvability, and low hygroscopicity.